How to add a webpart to a Sharepoint “NewForm.aspx”

I wanted to put a hidden CEWP on top of a standard SharePoint input form (you know when you click “NEW” too add an item to a list). The edit page was grayed out. I added to the querystring “NewForm.aspx?ToolPaneView=2” and I can add the CEWP to the top of the page. Once I added that, the edit page option is no longer grayed out.